Conan O’Brien, who’s already negotiated a $45 million exit deal from “The Tonight Show,” is looking for another windfall. The unemployed entertainer’s Central Park West penthouse duplex is quietly being shopped around with a $35 million price tag reports The Post’s Andy Wang. The south-facing co-op in the twin-towered Majestic at West 72nd Street comes with three terraces and dramatic park views. The apartment is a combination of an 18th-floor penthouse that O’Brien bought in 2007 for about $10 million and the combined-unit residence that he and his wife, Liza, already owned on the 17th floor. The building, on the former site of the Majestic Hotel, once housed mobsters including Mafia boss Frank Costello, who suffered only minor wounds when he was shot in the lobby during a failed assassination attempt in 1957.